Saiccor - The First 50 Years 5.8 MB - Sappi

The First Fifty Years
throughputs� However, signs of corrosion on the screens had been
observed� In January 1973 metallurgist Prof� Paul Robinson of the
University of the Witwatersrand was called in to examine the
corrosion� His conclusion was that pitting, crevice and stress corrosion
were taking place, particularly in the chlorine and chlorine dioxide
stages, and that either the process conditions (chlorides about 1 200
ppm, temperature 50 °C and above) or the material would have to be
changed� Neither was possible at the time (it was only some years
later that Kamyr developed titanium screens)� Corrosion continued,
and was continually repaired� Despite the plant running quite steadily,
the corrosion became a losing battle� By the middle of 1975 severe
corrosion cracking had taken place in the chlorine stage screens� Major
repairs were effected but by September 1975 severe cracking again
appeared� The decision was taken to cut out the screens and replace
them with washing filters� The chlorine screen was cut out
immediately and the plant restarted with all stages at low consistency
and no washing after the chlorine stage�
A filter building was erected adjacent to the plant and the first
washing filter was constructed from a spare Kamyr M57 drum, which
was started as a chlorine washer in March 1976� By this time three
Impco washers had been located in the US for immediate delivery�
After the Impco washers arrived, the diffusion screens were cut out
one after the other, approximately one month apart – the M57 washer
was changed to the chlorine dioxide stage� Towards the end of 1976
the diffusion bleach plant was gone – the screens were used to make
tiles for the washpit floors; strangely the screens from the hypo stage
were in perfect condition�
The only capital projects to come on stream before the end of 1975
were No 4 flock line and No 14 digester� No 4 flock line consisted of a
17A atritor and a small Hamworthy furnace which fed some 30 t/d
to the pulp from No 2 line, with the combined stream going to No 2
baling press� No 4 flock line was commissioned in February 1973�
The Board approved No 14 digester on 6 October 1972, for R340 000,
and it started cooking in October 1973�
Commissioning of No 5 flock line started in September 1975, but
made little contribution to production until 1976�
Towards the end of 1975 Lord Kearton retired� Although he last visited
Saiccor in October 1974, he remained a major driving force at Saiccor
until he retired from the Board on 14 November 1975�
After Kearton left, Courtaulds made it known they were no longer going
to carry out research on pulping for Saiccor, and further that they were
going to look at Saiccor’s quality far more critically, which was hardly
surprising as by 1976 Saiccor made up approximately 85 per cent of
Courtaulds’ pulp requirements� Kearton’s ‘that’s the pulp you get, that’s
the pulp you will use’ attitude to the Courtaulds Operations had gone�
80
Ennio Zan, with a 37,2 kg salmon
landed at the Mkomazi River
mouth on 29 December 1986
Paddy Brannigan (front left),
Norman Boulter (back) and Lord
Kearton (right), during the latter’s
last visit to Saiccor, 1974